If you select the last day, then select the first day when you get the range of selected days it reports the last day in the range as the first and the first day in the range as the last. It should probably have logic to return the chronological first and chronological last.
If you select the last day, then select the first day when you get the range of selected days it reports the last day in the range as the first and the first day in the range as the last. It should probably have logic to return the chronological first and chronological last.